A polymer formed article (e.g., plastic film) that is inexpensive and exhibits excellent workability has been provided with a desired function, and used in various fields.
For example, a gas barrier plastic film that does not allow water vapor and oxygen to pass through has been used as a food/drug packaging film in order to suppress oxidation and denaturation of proteins, oils, fats, and the like to keep taste and freshness.
In recent years, use of a transparent plastic film as an electrode substrate instead of a glass plate has been studied for displays (e.g., liquid crystal display and electroluminescence (EL) display) in order to implement a reduction in thickness, a reduction in weight, an improvement in flexibility, and the like. However, since a plastic film tends to allow water vapor, oxygen, and the like to pass through as compared with a glass plate, a deterioration in elements provided in a display may easily occur.
In order to solve the above problem, Patent Document 1 proposes a flexible display substrate in which a transparent gas barrier layer formed of a metal oxide is stacked on a transparent plastic film.
However, since the transparent gas barrier layer formed of a metal oxide is stacked on the surface of the transparent plastic film by deposition, ion plating, sputtering, or the like, cracks may occur in the gas barrier layer when the substrate is rolled up or bent, so that the gas barrier capability may deteriorate.
Patent Document 2 discloses a gas barrier laminate that includes a plastic film, and a resin layer that contains a polyorganosilsesquioxane as the main component and is stacked on at least one side of the plastic film.
However, since it is necessary to further stack an inorganic compound layer in order to obtain a gas (e.g., oxygen and water vapor) barrier capability, the process becomes complex, the production cost increases, or toxic gas may be used during the production process.
Patent Document 3 discloses a method that forms a polysilazane film on at least one side of a film, and subjects the polysilazane film to a plasma treatment to produce a gas barrier film.
When using the method disclosed in Patent Document 3, however, a sufficient gas barrier capability cannot be obtained unless the thickness of the gas barrier layer is reduced to a micrometer level. For example, Patent Document 3 states that a water vapor transmission rate of 0.50 g/m2/day is obtained when the gas barrier layer has a thickness of 0.1 μm.
Patent Document 4 discloses a film obtained by mixing an acrylic resin into a polysilazane film. However, the film disclosed in Patent Document 4 does not exhibit a sufficient gas barrier capability.